1. Field of the Invention
The present invention relates to a method for transferring rolls of paper, board and cellulosic web in a roll packaging system during wrapper winding, label attachment and header placement.
The invention also relates to an assembly for implementing the method.
2. Description of the Prior Art
The papermaking industry generally uses a packaging method wherein inner headers are first placed on the ends of a roll to be packaged, whereupon a wrapper is wound about the roll and finally the outer headers are placed on the roll ends. The packaging cycle and system themselves can be implemented in different ways and, typically, the packaging system is tailored to the needs of the mill. Inasmuch as the roll widths vary in a wide range, the wrapping method of the roll wrapper must be selected to meet the wrapping capacity needs. If an extremely high packaging capacity is required, wrapping stations can be used equipped with plural wrapper rolls of different widths of which a suitable wrapper can be selected for any roll to be packaged. However, this kind of wrapping station is very costly, whereby within the capacity limits of the station it may be more cost-advantageous to use, e.g., wrapping by overlapping layers, whereby two or more parallel wrapper courses are wound about the perimeter of the web roll. This kind of wrapping technique can be implemented using one or two wrapper widths thus allowing a very simple station layout. A disadvantage herein, however, is that either the roll being wrapped or the wrapping station itself must be moved during wrapping so as to allow the parallel wrapper courses to be wound.
In the above-mentioned overlap wrapping, the paper, board or cellulosic web rolls to be packaged are wrapped using a wrapper narrower than the roll to be wrapped. As the wrapper width is not sufficient to cover the entire perimeter width of the web roll, the roll is packaged by winding plural parallel wrapper turns thereabout. For such parallel overlap wrapping on a web roll, either the roll or the wrapper car or both must be moved parallel to the longitudinal axis of the roll. One technique of implementing the roll transfer is to move the roll being packaged on the cars of an intermittent-motion indexing conveyor. The indexing conveyor has separate stations for each packaging step: roll entry, buffer, wrapping, labeling and placement of outer headers, whereby one indexing conveyor car is located at each one of the stations. The car or cars are reciprocatingly moved between the stations so that after a car has moved a roll to the next station, the car is returned to its “home” position to be ready to receive a new roll to be transferred. To move the rolls forward, the indexing conveyor of the car(s) is moved upward, whereby the rolls thereon are elevated from the support rollers or support means of the station. As the car of the conveyor system has a fixed construction or, alternatively, the indexing car conveyor is comprised of cars connected together and moving in synchronism, all rolls are moved simultaneously. A roll transferred in this kind of system to the wrapping station is positioned by the movements of the indexing conveyor. Such a positioning of the web rolls at the wrapping station is unproblematic provided that the wrapper rolls with their feed assemblies are adapted movable at the wrapping station. However, if the wrapping station structures are stationary, lateral transfer of the roll at the wrapping station causes substantial time loss in overlap wrapping. Namely, the roll must be moved laterally in the direction of its longitudinal axis for winding the adjacent wrapper courses. Herein, an indexing conveyor is obviously problematic, because it forces all of the web rolls to move at the transfer of web roll being wrapped. Hence, after the completion of overlap wrapping of a roll, all the other rolls must be relocated back to their center positions at their respective stations by the movements of the indexing conveyor, which is a retarding step in the cycle time. While this may not necessarily drawback if only a small number of rolls are to be overlap wrapped, the roll sizes vary widely in modern papermaking mills, whereby the transfer movements of the indexing conveyor may give rise to a substantial reduction of available packaging capacity.